[23/24] libata: retry FS IOs even if it has failed with AC_ERR_INVALID

2.6.27-stable review patch. If anyone has any objections, please let us know.

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From: Tejun Heo <tj@kernel.org>

commit 534ead709235b967b659947c55d9130873a432c4 upstream.

libata currently doesn't retry if a command fails with AC_ERR_INVALIDassuming that retrying won't get it any further even if retried.However, a failure may be classified as invalid through hardwareglitch (incorrect reading of the error register or firmware bug) andthere isn't whole lot to gain by not retrying as actually invalidcommands will be failed immediately. Also, commands serving FS IOsare extremely unlikely to be invalid. Retry FS IOs even if it'smarked invalid.

Transient and incorrect invalid failure was seen while debuggingfirmware related issue on Samsung n130 on bko#14314.